The document discusses the male and female reproductive structures in plants. It describes the anatomy and development of anthers, pollen grains, pistils, ovules, and the process of fertilization. Key points include: - Anthers contain microsporangia that undergo meiosis to form pollen grains containing vegetative and generative cells. - Pistils contain ovules with nucelli containing embryo sacs developed from megaspores, which undergo double fertilization upon pollen tube growth. - Double fertilization involves the fusion of one sperm with the egg to form the zygote, and the other with the polar nuclei to form endosperm, leading to seed and fruit development.

1. Prepared by
TEJASVI BHATIA

3.  Modified stem have nodes and internodes
 Develops from floral primordia
 Primordia develop first into floral bud and
then into a flower.
 Reproductive part of plant
 Androecium is male reproductive whorl,
consists of stamens.
 Gynoecium is female reproductive part of
flower, consists of carpel(S).

4.  Male reproductive unit.
 Consists of two parts- fillament and anther
 Fillament is attached to thalamus or petal.

6.  Bilobed and dithecus.
 A longitudinal groove separate the theca.
 In a cross- section anther is a tetragonal
structure, consisting of 4 microsporangia,
two in each lobes.
 Later two microsporangia of each lobe fuse
as a pollen sac.

7.  A microsporangium is circular and surrounded
by 4 layers.
 These are epidermis, endothecium, middle
layers tapetum.
 Outermost layers protect the pollen and help
in dehiscence of anther to release pollen.
 Inner most layer of anther, pyramid shape
tapetum.

8.  Tapetum nourishes to developing pollen grains.
 When the anther is young a group of compactly
arranged homogenous cells called sporogenous
tissue occupies the centre of each
microsporangium.

10.  The process of formation of microspores from a
pollen mother cell through meiosis is called
microsporogenesis.
 The cells of sporogenous tissue undergo meiosis to
form microspore tetrad arranged in a cluster of 4
cells..
 As each cell of sporogenous tissue has potential to
form tetrad, so each cell is a microspore mother cell
(PMC).
 On maturation and dehydration of anther, the spores
dissociate and develop into pollen grains.
 Pollen grains release with the dehiscence of anther.

11.  Spherical in shape.
 Have two layered wall- outer hard exine layer and
inner thin intine.
 Exine- made up of sporopollenin. Resistant to organic
matter, withstand high temperature, acids, alkalis
and enzymes.
 It has prominent apertures called germ pores, where
sporopolenin is absent.
 Intine- It is thin, continuous layer, made of cellulose
and pectin.

12.  Pollen grain cytoplasm is surrounded by plasma membrane.
 Mature pollen grain has 2 cells- (i) vegetative cell
 (ii) generative cell.
 Vegetative cell- bigger, abundant food reserve, large
irregular nucleus.
 Generative cell- small, spindle shaped with dense
 cytoplasm and a nucleus, floats in vegetative cell cytoplasm.
 In 60% species pollen grains are shed in 2 celled stage where
as 40% species shed in 3 celled stage in which generative
cell divides mitotically into 2 male gametes.

14.  Pistil- female reproductive part of flower.
 It may be mono or bi or tri or polycarpellary,
syncarpous or apocarpous.
 Each pistil consists of ovary, style and stigma.
 The ovary has one or more cavities called locules.
 Placenta in locules bears ovules.
 Number of ovules may be one or more.

15.  Arises as primordium on placenta.
 The short stalk which attach ovule with
placenta is funicle.
 The primordium grows into a mass of cells
forming nucellus, the body of ovule.
 The two protective covering of nucellus is
integuments, except at the tip leaving a
small opening called Micropyle.

16.  Basal part of ovule is called chalaza that lie
opposite to micropyle.
 Cells of nucellus are rich in reserve food.
 A single embryo sac or female gametophyte
located in the nucellus, which is developed
from megaspore.

18.  One of the nucellar cell in the micropylar region is
differentiated into megaspore mother cell.
 The cell is larger, contains dense cytoplasm and a
prominent nucleus.
 It undergoes meiosis forming 4 haploid cells called
megaspore tetrad.
 3 megaspores degenerate and only one megaspore
become functional.

19.  Functional megaspore is the first cell of female
gametophyte.
 Its nucleus undergoes mitosis and the two nuclei
move to opposite poles and form 2 nucleate embryo
sac.
 Two successive mitotic division in each of these 2
nuclei form an 8 nucleate embryo sac.

20.  Simultaneous maturation of anther and pistil.
 Anther and stigma lie close to each other.
 Cleistogamous flower (oxalis,
commelina,viola)

21.  Unisexual flower and diocious plants.
 Pollen release and stigma receptivity are not
 synchronised.
 Different orientation of anther and stigma of
 flower.
 Self incompability.

22.  Pollen grains are light, nonsticky/ dry,
sometimes winged.
 Well exposed anther.
 Large feathery stigma.
 Flowers arranged as inflorescence.
 Single ovules.

23.  Seen in submerged flowers like Vallisneria and
Hydrilla and Zostera.
 In Vallisneria male flowers released on water
surface and female flowers reaches the surface for
pollination.
 In sea grasses, pollen grains are long ribbon like and
carried passively to submerged female flowers.
 Mucilage coated pollen grains.

24.  Large
 Brightly coloured and showy.
 If flowers are small, grouped into
inflorescence.
 Highly fragrant
 Produce nectar
 Sticky pollen and stigmatic surface
 Provide rewards to animal pollinator such as
nectar, food (pollen) or provide safe place
for laying eggs.

25.  Recognition of compatible pollen-It is the
interaction between chemical components of
pollen and those of stigma.
 Germination of pollen and development of
male gametophyte-
 (a) compatible pollen starts its germination,
stimulated by certain secretion of stigma.
 (b) intine grows out through one of germ pore.
 (c) content of pollen moves into the tube i.e.
vegetative and generative / 2 male gametes.

26.  (d) pollen tube grows through the tissues of stigma and
style by secreting enzymes to digest them and enters
ovule through micropyle.
 (e)It enters the embryo sac through filliform apparatus of
one synergids to liberate male gametes.
 (f) germinated pollen grain with pollen tube carrying
vegetative nucleus and 2 male gametes is the fully
developed female gametophyte.

28.  Release of 2 male gametes from pollen tube into
cytoplasm of synergids.
 Fusion of one male gamete with egg cell called
Syngamy and form zygote(2n) which develops
into embryo.
 Fusion of 2nd male gamete with polar nuclei of
central
 cell to form PEN(3n).
 As syngamy and triple fusion occur in an embryo
sac, the phenomenon is known as double
fertilisation.
 Central cell with PEN is called PEC which
develops into endosperm.

29.  Development of endosperm
 Development of embryo
 Maturation of ovule into seed
 Maturation of ovary into fruit.

30.  Its development precedes embryo
development.
 There are 3 methods of embryo development
: nuclear, cellular, helobial.
 In nuclear type PEN divides mitotically
without cytokinesis and endosperm is free
nuclear, then cell wall formation starts from
periphery and endosperm become nuclear.
 It provides food to developing embryo.
 If endosperm is completely utilised by
embryo, seed is non-albuminous, if present
,seed is albuminous.

32.  It starts after certain embryo formation.
 Zygote divides mitotically and form
proembryo.
 Then it develops into globular and heart
shaped embryo and then horse shoe shaped
mature embryo with one or two cotyledon.

33.  Seeds are formed without fertilisation.
 It may develop if a diploid egg cell develops into
embryo without fertilisation.
 If cells of nucellus may develop into embryo and
pushed into the embryo. Example citrus and mango.

34.  If more than one egg may form in embryo sac.
 If more than one embryo sac formed in an ovule.
 Other cells like synergids or nucellus develop into
embryo.
 E.g. orange, lemon, mango, onion, groundnut etc.